- Electricity (on the rise; about one-third of U.S. homes use it for primary heat);
- Heating oil (prices are tied to world events; 6% of U.S. homes use it for primary heat, mostly in the Northeast);
- Natural gas (huge supply forecast; nearly half of U.S. homes use for primary heat); and
- Propane (a relatively clean fuel but losing popularity; cost varies a lot by region).
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